Systems for controlling a fuel blend for a gas turbine

Abstract

A fuel control system for a turbine engine includes a mixer for mixing first and second fuels to obtain a fuel blend, a fuel blend analyzer, a combustor operable with the fuel blend, and a knock sensor coupled to the combustor. The system also includes a controller configured to: receive a measurement indicative of a composition of the fuel blend; compare the fuel blend measurement to an operational model of the combustor; determine, based on the comparison, a predicted combustion condition in the combustor associated with the fuel blend measurement; control, based on the predicted combustion condition, flow of the first fuel or the second fuel; receive a combustion signal indicative of combustion behavior in the combustor; compare the predicted combustion condition to the combustion signal; and update the operational model if the predicted combustion condition does not match the indicated combustion behavior.

What is claimed is: 
     
         1 . A fuel control system for a turbine engine, said system comprising:
 a fuel supply system comprising a mixer for use in mixing a first fuel and a second fuel together to obtain a fuel blend;   a fuel blend analyzer downstream from the mixer;   a combustor downstream from the fuel blend analyzer, the combustor operable with the fuel blend;   a knock sensor coupled to the combustor;   at least one second sensor coupled to the combustor, the at least one second sensor formed as one of an optical sensor, a temperature sensor, or a pressure sensor; and   a controller communicatively coupled to the knock sensor, the at least one second sensor, and the fuel blend analyzer, the controller comprising at least one processor in communication with at least one memory device, the at least one processor configured to:
 receive, from the fuel blend analyzer, a measurement indicative of a composition of the fuel blend; 
 compare the fuel blend measurement to an operational model of the combustor; 
 determine, based on the comparison, a predicted combustion condition in the combustor associated with the fuel blend measurement; 
 control, based on the predicted combustion condition, at least one of a flow of the first fuel and a flow of the second fuel, wherein the first fuel is one of a natural gas, a liquefied petroleum gas, and a hydrocarbon gas fuel; 
 combust the fuel blend in the combustor; 
 receive, from the knock sensor and the at least one second sensor, combustion signals indicative of combustion behavior in the combustor; 
 compare the predicted combustion condition to the combustion signals; 
 determine whether the predicted combustion condition matches the combustion behavior indicated by the combustion signals; and 
 update the operational model if the predicted combustion condition does not match the indicated combustion behavior, wherein the updating includes at least one of associating a measurement of the fuel blend with an operating parameter monitored by the at least one second sensor, and changing the operational model. 
   
     
     
         2 . The system according to  claim 1 , wherein the fuel blend analyzer comprises a specific gravity sensor or a density meter. 
     
     
         3 . The system according to  claim 1 , wherein the second fuel is hydrogen. 
     
     
         4 . The system according to  claim 1 , further comprising an additional sensor communicatively coupled to the controller, the additional sensor selected from the group consisting of an exhaust gas emissions sensor, an exhaust gas temperature sensor, a combustion pressure sensor, a fuel blend flow sensor, a first fuel flow sensor, a second fuel flow sensor, a first fuel composition sensor, a second fuel composition sensor, and an optical flame sensor. 
     
     
         5 . The system according to  claim 4 , wherein the additional sensor is an optical flame sensor. 
     
     
         6 . The system according to  claim 4 , wherein the additional sensor is a first fuel composition sensor or a second fuel composition sensor. 
     
     
         7 . The system according to  claim 1 , wherein the combustor is a staged combustor comprising a first stage and a second stage. 
     
     
         8 . The system according to  claim 7 , wherein a first portion of the first fuel is supplied to the first stage, and a second portion of the first fuel is supplied to the mixer for use in mixing the second portion of the first fuel and the second fuel together to obtain the fuel blend. 
     
     
         9 . The system according to  claim 7 , wherein the staged combustor is an axially-staged combustor. 
     
     
         10 . The system according to  claim 1 , wherein the second fuel is a liquefied hydrocarbon fuel. 
     
     
         11 . A fuel control system for a turbine engine, said system comprising:
 a fuel supply system comprising a mixer for use in mixing a first fuel and a second fuel together to obtain a fuel blend;   a fuel blend analyzer to obtain a fuel blend measurement indicative of a composition of the fuel blend;   a combustor downstream from the mixer, the combustor operable with the fuel blend;   a plurality of sensors coupled to the combustor to obtain combustion signals indicative of combustion behavior in the combustor, the plurality of sensors including a knock sensor coupled to the combustor and at least one additional sensor coupled to the combustor; and   a controller communicatively coupled to each of the plurality of sensors sensor and the fuel blend analyzer, the controller comprising at least one processor in communication with at least one memory device, the at least one processor configured to:
 compare the fuel blend measurement to an operational model of the combustor; 
 determine, based on the comparison, a predicted combustion condition in the combustor associated with the fuel blend measurement; 
 control, based on the predicted combustion condition, at least one of a flow of the first fuel and a flow of the second fuel, wherein the first fuel is one of a natural gas, a liquefied petroleum gas, and a hydrocarbon gas fuel; 
 combust the fuel blend in the combustor; 
 compare the predicted combustion condition to the combustion signals obtained by each of the plurality of sensors coupled to the combustor; 
 determine whether the predicted combustion condition matches the combustion behavior indicated by the combustion signals; and 
 update the operational model if the predicted combustion condition does not match the indicated combustion behavior, wherein the updating of the operational model includes at least one of associating a measurement of the fuel blend with an operating parameter monitored by the at least one additional sensor of the plurality of sensors, and changing the operational model. 
   
     
     
         12 . The system according to  claim 11 , wherein the at least one processor is further configured to control the at least one of the flow of the first fuel and the flow of the second fuel by transmitting an output signal to at least one control valve upstream from the mixer. 
     
     
         13 . The system according to  claim 11 , wherein the fuel blend analyzer is located downstream from the mixer, and wherein the at least one processor is further configured to:
 receive, from at least one fuel sensor upstream from the mixer, at least one measurement indicative of a composition of at least one of the first fuel and the second fuel;   determine, based on the fuel blend measurement and the at least one measurement of the at least one of the first fuel and second fuel, the composition of the fuel blend;   compare the determined composition of the fuel blend to the operational model of the combustor; and   determine, based on the comparison of the determined composition of the fuel blend to the operational model of the combustor, the predicted combustion condition.   
     
     
         14 . The system according to  claim 11 , wherein the at least one processor is further configured to:
 compare the fuel blend measurement to an emissions model of the combustor;   determine, based on the comparison of the fuel blend measurement to the emissions model of the combustor, a predicted level of pollutants associated with the fuel blend measurement; and   control, based on the predicted level of pollutants, by the controller, at least one of the flow of the first fuel and the flow of the second fuel.   
     
     
         15 . The system according to  claim 14 , wherein the at least one processor is further configured to:
 receive, from an emissions sensor downstream from the combustor, an emissions level measurement;   compare, the predicted level of pollutants to the emissions level measurement;   determine whether the predicted level of pollutants matches the emissions level measurement; and   update the emissions level model if the predicted level of pollutants does not match the emissions level measurement.   
     
     
         16 . The system according to  claim 11 , wherein the second fuel is hydrogen. 
     
     
         17 . The system according to  claim 11 , wherein the second fuel is a liquefied hydrocarbon fuel.